A known backrest of this type has a spinal support in the form of a resilient pressure pad which is disposed so as to be located between the sixth and eighth dorsal vertebra of the person sitting in the chair. Use of this known backrest had led to a reduction in the number of posture problems due to prolonged sitting in office chairs. However, a disadvantage of the known backrest is that the amount of resilience at the resilient area which acts upon the muscles or nerves of the user, is not capable of being adjusted.